Re: SLAPD denial of connections under load

[Howard Chu <hyc@symas.com>]

Quanah Gibson-Mount wrote:

> --On Wednesday, August 11, 2004 8:43 PM -0400 James Courtney 
> <Jcourtney@inphonic.com> wrote:

> > Our other problem is that under high load from the mail server we see
> > that Maildrop claims it cannot connect to the LDAP server.  They are on
> > the same system and Maildrop connects to localhost rather than going out
> > over the network and back.  Maildrop's ldap_simple_bind_s is returning 81
> > (0x51) which is defined as the constant LDAP_SERVER_DOWN.  The server has
> > been up for 24 hours now and is generally responsive though so this is
> > confusing.  Under what conditions would slapd not accept a network
> > connection?  Threads + backlog exceeded?

> I suggest you separate the mail server from the LDAP server.  The high 
> load on the system from the mail delivery agent may be preventing slapd 
> from responding.

There isn't enough information here to determine a course of action. You 
need to get more info before making suggestions on how to fix the problem.

My guess is that slapd is out of file descriptors or there are too many 
outstanding connections. Using a program like lsof may help to determine 
if that's the case. There is no way that any mail server can generate 
more queries than slapd can handle when both are running on the same CPU.
--
  -- Howard Chu
  Chief Architect, Symas Corp.       Director, Highland Sun
  http://www.symas.com               http://highlandsun.com/hyc
  Symas: Premier OpenSource Development and Support